Cleaning agent based on cycloalkanes

ABSTRACT

The use of a mixture of cycloalkanes of general formula C n  H 2  (n+1-a) in which n is an integer ranging from 8 to 12 and a represents the number of rings as agent for cleaning and degreasing solid surfaces, e.g., printed circuits. The mixture has a flash point above 55° C. (ASTM D56-70) and a distillation range of 175° C. to 235° C.

This is a national stage application of PCT/FR96/00584 filed Apr. 17,1996.

FIELD OF THE INVENTION

The present invention relates to cycloalkanes which can be used ascleaning and degreasing agents, in a machine and in a non-aqueousmedium, of solid surfaces such as metal components, ceramics, glass andplastics which have been soiled by machine oils or greases and/or oilsor greases for their temporary protection.

These cycloalkanes can also be used for defluxing printed circuits. Thisdefluxing operation consists in removing the welding flux.

BACKGROUND OF THE INVENTION

Hitherto, hydrocarbon solvents were used for these various operationsand mainly chlorinated solvents such as, in particular,1,1,1-trichloroethane, known in the art by the name T 111, as well aschlorofluoroalkanes such as 1,1,2-trichloro-1,2,2-trifluoroethane, knownin the art by the name F 113.

However, these chloro and fluorochloro compounds are suspected of beingresponsible for the decrease in the stratospheric ozone layer whichprovides protection against certain radiations.

Following the Montreal Protocol which results from recent internationaldiscussions on the environment, these chloro or fluorochloro compoundswill before long need to be replaced by substitutes having little or nodestructive effect with respect to stratospheric ozone.

British patent application GB 2,175,004 proposes a cleaning compositionfor removing greases from metal or plastic surfaces, comprising from 85to 97 parts by weight of non-aromatic hydrocarbons containing aliphaticand/or cycloaliphatic compounds and from 3 to 15 parts by weight ofaromatic compounds containing at least one alkyl group having from 8 to18 carbon atoms.

However, this composition has the drawback of containing non-negligibleamounts of aromatic compounds.

On account, in particular, of their relatively irritant nature, the useof such compounds in degreasing applications is seen to be increasinglylimited, or even prohibited.

Application WO 91/19831 describes a composition comprisingcycloparaffins, branched paraffins and at least one surfactant.

European patent application EP 0,474,053 describes, in Example 1thereof, a composition consisting of:

69% by weight of cycloparaffins,

29% by weight of isoparaffins,

2% by weight of n-paraffins,

and traces of aromatic compounds.

Application WO 93/06204 relates to a composition consisting essentiallyof:

1) 30 to 70% by volume of a glycol ether,

2) 30 to 70% by volume of one or more linear, branched or cyclicaliphatic hydrocarbons having from 12 to 18 carbon atoms,

3) from 0 to 10% by volume of at least one surfactant, and

4) from 0 to 5% by volume of at least one inhibitor, fragrance or dye.

Application WO 93/13246 relates to a composition comprising:

i) from 75 to 90 parts by volume of a distillation fraction obtained bydistillation of petroleum, the said fraction containing not less than92% by weight, based on the total weight of the fraction, ofhydrocarbons chosen from naphthenic and paraffinic hydrocarbons havingfrom 8 to 15 atoms, and

ii) 5 to 25 parts by volume of one or more branched or unbranchedsaturated aliphatic alcohols having from 5 to 15 carbon atoms.

Chemical Abstracts, Vol. 115, No. 16, No. 161650 relating toJP-A-03062896, describes a cleaning composition containing at least 70%by weight of a saturated cyclic hydrocarbon having from 9 to 18 carbonatoms, and 0.1 to 30% by weight of an aliphatic alcohol having from 6 to18 carbon atoms and/or a nonionic surfactant.

SUMMARY OF THE INVENTION

It has now been found that a practically pure cycloalkane or a mixtureof cycloalkanes having a flashpoint above 55° C., measured according toASTM standard D56-70, and a distillation range of from 175° C. to 235°C. could be used as an agent for cleaning and degreasing solid surfaces.

In the present case, the expression mixture of cycloalkanes denotes amixture of saturated mono- or polycyclic hydrocarbons, optionallysubstituted with one or more alkyl residues, of general formula C_(n) H₂(n+1-a)(I) in which n is an integer ranging from 5 to 26 and arepresents the number of rings.

According to the present invention, a mixture of cycloalkanes of formula(I) in which n is an integer ranging from 8 to 12, and preferablyranging from 9 to 11, and a is an integer ranging from 1 to 5, andpreferably ranging from 1 to 3, will preferably be used.

By way of illustration of such mixtures which can be used according tothe present invention, mention may be made of the mixtures of(alkyl)cycloalkanes obtained by catalytic hydrogenation of petroleumfractions consisting of aromatic and/or cyclodienic compounds such as,in particular, alkylbenzenes, divinylbenzenes, dicyclopentadiene,alkyldicyclopentadienes, and naphthalene and its alkylated derivatives.

The mixtures of (alkyl)cycloalkanes thus obtained essentially consist ofsaturated cyclic hydrocarbons which may have one or more alkyl residueshaving from 1 to 4 carbon atoms.

Illustrations of such mixtures which may be mentioned are mixturescontaining two or more of the following compounds:tetrahydrodicyclopentadienes, methyltetrahydrodicyclopentadienes,dimethyltetrahydrodicyclopentadienes, ethylpropylcyclohexanes,alkyldecahydronaphthalenes.

According to the present invention, mixtures containing at least 40% byweight of endo-tetrahydrodicyclopentadiene will preferably be used.

According to the present invention, petroleum fractions referred to asnaphthenic fractions may also be used as the mixture of cycloalkanes.

These naphthenic fractions essentially consist of compounds of formula(I) in which a=1, 2 or 3 and n is generally between 9 and 12.

Examples of such naphthenic fractions which may be mentioned are thenaphthenic solvents sold by Exxon Chemical under the name Nappar 11.

Examples of practically pure cycloalkanes which may be mentioned arecyclodecane, tricyclo 6.2.10.²,6 ! decane and bicyclohexyl.

The mixture of cycloalkanes according to the present invention has theadvantage of having flashpoints above 55° C., which allows it to be usedwithout danger in machines in which so-called A3 solvents are used, thatis to say solvents whose flashpoint is between 55° C. and 100° C.

Accordingly, the mixture of cycloalkanes of the present invention may beused most particularly in so-called closed systems in which thetemperatures may reach 40° C., or even higher, in order to clean solidsurfaces such as metal and/or plastic components and in order to defluxprinted circuits.

The mixture of cycloalkanes of the present invention may be stabilized.

Stabilizing agents which may be used are nitro derivatives such asnitromethane, nitroethane, nitropropane and nitrotoluene; ethers oracetals such as dimethoxymethane, 1,3-dioxolane and dimethoxyethane;amines such as triethylamine, dipropylamine and dimethylamine;phosphorus derivatives such as triisodecyl phosphite and triisooctylphosphite.

The mixture of cycloalkanes may also contain one or more odour-maskingagents.

Examples of such products which may be mentioned are vanillin and itsderivatives, and essences of pine.

These compounds are used in very low amounts, generally between 0.01 and0.1 part by weight per 100 parts by weight of the mixture ofcycloalkanes.

The mixture according to the invention has the advantage of beingreadily removed after the degreasing operation.

The examples which follow illustrate the invention.

In these examples, the flashpoints are determined according to ASTMstandard D56-70.

The following compounds were used:

"Nappar 11" naphthenes (referred to hereinbelow as Nap 11). Thiscycloalkane fraction has a distillation range of from 182° C. to 200° C.and a flashpoint of 60° C.

A mixture of cycloalkanes containing about 40% by weight ofendo-tetrahydrodicyclopentadiene (referred to hereinbelow as THDCPD)having a distillation range of from 180° C. to 210° C. and a flashpointof 58° C.

EXAMPLE 1

A 40×30 mm stainless steel grille is weighed after coating with a wholeoil or water-soluble oil supplied by Castrol, Shell, Mobil or Elf, andis degreased at a temperature of about 40° C. by mechanical stirring ina vessel containing Nap 11.

Within 30 seconds, no further trace of oil remains on the grille.

EXAMPLE 2

The process is performed as in Example 1, replacing the Nap 11 byTHDCPD. The cleaning performances are identical. In 30 seconds, thegrille is totally free of oil.

EXAMPLE 3

(Defluxing Test)

125 ml of THDCPD are introduced into each tank of a small laboratorytwin-tank machine equipped with an ultrasound generator, and the liquidin each tank is then brought to 40° C.

Five standardized circuits (model IPC-B-25) coated with rosin-basedsoldering flux (flux R8F from the company Alphametal) annealed at 230°C. for 30 seconds and cooled, are immersed in the liquid at 40° C. underultrasound for three minutes. The circuits are drained for one minuteand then rinsed for three minutes in the second tank and aresubsequently drained for a further minute and finally dried at 55° C.

The drying time is 75 seconds. The quality of the cleaning is evaluatedby determining the level of ionic residue according to the standardizedprocedure IPC-TM 650 No. 2.3.25 and 2.3.26, and according to thestandard MIL-STD-2000.

The value obtained, 1.52 μg eq. NaCl/cm² is very much lower than thethreshold (2.5 μg.eg.NaCl/cm²) which is tolerated in the electronicsfield.

We claim:
 1. In a method comprising cleaning, degreasing or defluxingsolid surfaces with a cleaning, degreasing or defluxing agent, theimprovement wherein the cleaning degreasing or defluxing agent consistsessentially of a mixture of cycloalkanes which has flash point above 55°C., measured according to ASTM standard D56-70, and a distillation rangeof from 175° C. to 235° C., and from 0 up to 0.1 parts by weight of eachof a stabilizing agent and an odor masking agent based on 100 parts byweight of said mixture of cycloalkanes, said mixture of cycloalkanesbeing a mixture of saturated mono or polycyclic hydrocarbons, optionallysubstituted with one or more alkyl residues, of general formula

    C.sub.n H.sub.2 (n+1-a)                                    (I)

in which n is an integer ranging from 8 to 12 and a is an integerranging from 1 to
 5. 2. A method according to claim 1, characterized inthat, in the formula (I), n is an integer ranging from 9 to 11 and a isan integer ranging from 1 to
 3. 3. A method according to claim 2,wherein solid surfaces comprising printed circuits.
 4. A methodaccording to claim 2, wherein solid surfaces comprising metal and/orplastic components.
 5. A method according to claim 1, wherein themixture of cycloalkanes is a mixture containing at least 40% by weightof endotetrahydrodicyclopentadiene.
 6. A method according to claim 5,wherein solid surfaces comprising printed circuits.
 7. A methodaccording to claim 5, wherein solid surfaces comprising metal and/orplastic components.
 8. A method according to claim 1, characterized inthat the mixture of cycloalkanes is a naphthenic fraction.
 9. A methodaccording to claim 8, characterized in that the naphthenic fractionconsists essentially of compounds of formula (I) in which a=1, 2 or 3and n is between 9 and
 12. 10. A method according to claim 9, whereinsolid surfaces comprising printed circuits.
 11. A method according toclaim 9, wherein solid surfaces comprising metal and/or plasticcomponents.
 12. A method according to claim 8, wherein solid surfacescomprising printed circuits.
 13. A method according to claim 8, whereinsolid surfaces comprising metal and/or plastic components.
 14. A methodaccording to claim 1, wherein solid surfaces comprising printedcircuits.
 15. A method according to claim 1, wherein solid surfacescomprising metal and/or plastic components.
 16. A method according toclaim 1, wherein said cleaning, degreasing, or defluxing agent consistsof said mixture, including said stabilizing and odor masking agents.